Effect of nitroglycerin on aortic impedance, diameter, and pulse-wave velocity

The effects of an intravenous infusion of 1 |xg/kg/min nitroglycerin were studied on systemic arterial properties in nine acutely instrumented dogs. Aortic impedance and pulse-wave velocity were calculated from measured pressure and flow signals collected during random ventricular pacing. Central aortic diameter was simultaneously determined with ultrasonic dimension crystals. Mean blood pressure was maintained constant to avoid the confounding effects of passive, pressure-induced changes in vascular properties. Nitroglycerin both reduced the amplitude of peripheral vascular reflections and delayed the return of these reflections to the aortic root. This reflection delay was manifested as a consistent leftward shift in both impedance modulus and phase. The magnitude of this reflection delay could not be entirely accounted for on the basis of the measured changes in average pulse-wave velocity along the aorta. (Circulation Research 1988;62:884-890) The beneficial effects of nitroglycerin on myo-cardial ischemia may be mediated in part bychanges in ventricular loading. ' The ability of nitroglycerin to reduce ventricular preload by veno-dilation has been extensively documented. Although the effects of nitroglycerin on ventricular afterload have received much less attention, recent studies b